1. Field of the Invention
The present invention relates to multilayer electronic components and multilayer array electronic components, and more specifically, to a multilayer electronic component and a multilayer array electronic component, each including a multilayer composite including a circuit element that is formed by stacking electrical conductors and insulating layers.
2. Description of the Related Art
A known multilayer array electronic component includes a metallic direction identification mark provided on the upper surface of a multilayer composite (see Japanese Unexamined Patent Application Publication No. 2005-64267). The direction identification mark provides identification of the direction of the multilayer array electronic component, which is asymmetrical and accordingly has a direction in which it should be mounted. The direction identification mark prevents mounting errors and production errors.
However, the direction identification mark is provided on the upper surface of the multilayer composite of the multilayer array electronic component, and it is difficult to form the direction identification mark in a precise shape by electrolytic plating. This problem results in errors in identifying the direction of the multilayer array electronic component. How the error occurs will be described in detail below.
The direction identification mark is formed by electrolytically plating an underlayer with a Ni plating layer and a Sn plating layer. The underlayer is formed of Ag, Pd, Cu, Au, or an alloy of these metals by screen printing or other suitable method.
In order to form the plating layers, a ceramic composite and metal balls are placed in a vessel equipped with a cathode containing a plating solution, and electricity is supplied to the underlayer through the cathode, the metal balls, and the contacts between the metal balls and the underlayer. In order to form sufficiently thick plating layers with relatively small variations among products by electrolytic plating, the metal balls and the underlayer must be in contact with each other over as large an area as possible.
However, the underlayer of the direction identification mark is formed only on the upper surface of the ceramic composite. Therefore, the underlayer may not be sufficiently in contact with the metal balls during electrolytic plating. If the underlayer of the direction identification mark is not in contact with the metal balls, a sufficiently thick plating layer cannot be formed on the underlayer, and the underlayer may be exposed.
In order to identify the direction of the multilayer array electronic component, an image recognizer is typically used. More specifically, the image recognizer photographs the upper surface of the multilayer array electronic component with a camera, and the image is converted into binary data. The shape of the direction identification mark is thus recognized to identify the direction of the multilayer array electronic component. If the underlayer of the direction identification mark is exposed, the image recognizer may not recognize that the exposed portion of the underlayer is a portion of the direction identification mark. Thus, the image recognizer may incorrectly identify the shape of the direction identification mark and fail to correctly identify the direction of the multilayer array electronic component.